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Harry Sedgwick8/10/07

Chromatography practical-write up

Aim: - Was to find out the amino-acids in the mixture using theChromatography paper and equipment.

Introduction: - Chromatography is a method of separating amixture of compounds by the use of a porous material. Usingchromatography paper I will determine what amino-acids are in themixture of substances- these amines being: valine, glylcine, leucine,alaline. The amines will travel different distances from the origintherefore showing what the amines are in the mixture. There isdifferent chromatography to E.G two way chromatography- this iswhen a mixture of amines is put on one spot in the corner of a pieceof Chromatography paper therefore it can be checked twice:(diagram to visualise):

The RF (Retardation factor) can be illustrated easily as well:

Safety:-There are some procedures in this experiment that need tobe carried out with caution e.g. the Ninhydrin in this experiment(liquid substance in which the paper will be soaked in before heated)is a cancerous material and also the heating of the paper requiresgreat safety issues so students cannot deal with these proceduresonly teachers can safely take care of this. We also need to wearoveralls and gloves in this experiment to not contaminate ourexperiment and ourselves.

Apparatus:- we need some equipment to complete this practical,this being:-

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Chromatography paper.

The right amines (valine, glycine, leucine, alaline) and themixture we have to find the contents of.

5 different pipettes, 1 for each amine therefore preventingcontamination.

Gloves and overalls.

Ruler and pencil for marking points on the paper.

And the oven chromatography equipment needed by teachersto complete the experiment : ninhydrin for soaking in achromatography jar and an oven set to 100 degrees

Diagrams of equipment needed:-

Method:- Firstly I put my gloves and overalls on and cleaned thetable I was working on ( to prevent contamination). I then markedthe initial points on my Chromatography paper e.g. the origin lineand 5 crosses indicating where to put my amines and the mixture.After that I started to put my amines on the paper on the rightpoints marked 1-5 e.g.:1-2-3-4-5- MixtureI had to be careful that I did not apply too much on the crossesbecause I did not want the amine to spread. I then had to wait for itto dry to apply another dot of the same amine on each spot to get amore concentrated dot. I then gave it to a teacher to process the

rest of the experiment - to put in the chromatography jar and thenput in the oven at 100 degrees.

Conclusion:- I could have carried out this experiment much moreefficiently by using different methods- if I had the time. I could haveused a smaller pipette end:

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This would help because it would give a spot that is more definedtherefore a spot of amine that is a lot less likely to merge with otheramines. We could also apply more amine to one spot using thesmaller pipette (remembering to let the amine dry before the nextapplication). I could have also used more covering on the table and

myself to lower the level of contamination. Lastly I think I shouldhave made another copy of the experiment and maybe used 2-waychromatography to get better results.